The present invention relates to a method for determining the availability of at least one of a plurality of different services.
In wireless cellular telecommunication networks, the network is divided into a plurality of cells each of which is served by a base station. Each base station is arranged to communicate with mobile terminals in the cell associated with base station. Known networks are arranged to deal with different information rates. For example, some voice information services can require a lower rate as compared to certain types of data information services. Other types of data services may only require a lower rate than voice services, for example some types of packet services.
Code division multiple access (CDMA) systems have been proposed for cellular networks. For example, the IS-95 system in the USA uses code division multiple access. In these system a plurality of users in a given cell will use the same frequency at the same time. The users are distinguished by different spreading codes. When the number of users becomes large, interference between the users increases. This makes it harder to receive all the information correctly. Accordingly, a threshold is set and when the interference exceeds this level, no additional users are permitted to use the cell in question. If the threshold is too high, a CDMA system might become unstable. On the other hand, if the threshold is too low, the capacity of the network is unnecessarily reduced. In a cell, higher bit rates can be used nearer the base station as compared with at the cell boundaries as the power requirement is much lower nearer the base station as compared to at the cell edge. Data transmission can take place at different bit or information rates as discussed hereinbefore. When the bit rate is increased, the transmitted power needs to be increased in order to maintain the required quality.
In the third generation systems which are currently being proposed, it is envisaged that services other than just voice and data services may be provided. For example, data packet services and video information may also be transmitted and received. It has also been proposed that more than one application take place at the same time. For example a user may conduct a conversation at the same time that he sends a facsimile. The problems discussed hereinbefore will become of even more concern in these proposed third generation systems.
It is an aim of embodiments of the present invention to reduce or overcome these disadvantages.
By way of background, reference is made to Finish patent application No. 971927, in the name of the present applicant. This patent application relates to a proposed third generation systems such as UMTS (Universal Mobile Telecommunications System). In this proposed system, there are three or four different operating environments. These operating environments are: vehicular environment which utilises cells covering several kilometres; pedestrian environment which utilises cells covering hundreds of metres; office environment which utilises cells covering only a relatively few metres; and possibly the satellite environment which utilises cells which cover several hundreds of kilometres. These different environments may support different maximum data rates. For example, the maximum data rate supported by the vehicular environment may be less than that supported by the office environment. In practice these different cells may overlie one another so that a mobile station may be in different types of cells at the same time. The mobile terminal thus collects information about the service provided by each base station of these different cells. The mobile station predicts the type of service, including the data rate, which it will require in the next connection. The mobile terminal will be connected to cell which provides the predicted type of service. One main problem with the arrangement disclosed in this document is that the xe2x80x9cend-userxe2x80x9d does not know which services can be used at the user""s location with respect to the base station with the current cell loading.
According to one aspect of the present invention, there is provided a method of determining the availability of at least one of a plurality of different services in a wireless communication network comprising at least a first station and a second station which are in communication, said method comprising the steps of estimating the pathloss between said first station and said second station, and based on said pathloss and the requirements of at least one of said services, determining the power with which said first station is required to transmit to said second station; and comparing said required power with the maximum power with which the first station is capable of transmitting.
Thus, in preferred embodiments of the present invention, a determination may be made as to the availability of a service before a connection using a particular service is attempted. A user may be able to determine whether or not a service might be available without using up network capacity in attempting to make a connection which will fail. The user may be provided with an indication of the available services.
Preferably, the method further comprises the step of determining if said first station is able to provide said service based on said comparing step.
The first station may be arranged to estimate the pathloss between said first and second stations. Preferably, the pathloss estimate is determined from information transmitted from the second station as to the power at which signals are transmitted from the second station and measurements at the first station as to the strength of signals received at the first station from the second station. The second station may transmit information to the first station as to the interference levels occurring in the signals received by the second station from the first station.
The determining step preferably takes into account the interference level occurring in transmissions between said first and second stations.
If the interference is taken into account, it may be determined whether or not the second station is able to support a given service. Information relating to the maximum permitted interference level for signals which are transmitted from the first station to the second station may be transmitted to the first station from the second station. The level of interference which would occur in the signals transmitted between the first and second station may be estimated from the current level of interference occurring in the signals transmitted between the first and second stations and the additional interference which would occur if the first station were to use one of said available services. Preferably, the current level of interference is obtained from information provided by the second station,
The estimated level of interference may be compared with the maximum level of interference.
If the current level of interference between the first and second stations is the same as the maximum level of interference, then it is determined that none of the plurality of services are available.
The availability of services may be determined from the maximum power by determining the greatest level of service which can be provided. This then allows the user to select services have the determined greatest level or services having lower requirement levels.
An indication as to the availability of a given service may be provided by said first station. For example a suitable indication may be displayed on the display. The displayed availability may include a scale indicative of the level of service requirements which are available. Alternatively or additionally, the services which are available may be displayed. Preferably, said plurality of services have different minimum requirements. The at least one minimum requirement is taken into account when determining the availability of at least one service. The service requirements may include one or more of the following: bit rate and quality (eg, energy per bit requirement).
The information determined by the first station in the determining step may be used by the wireless communication network to calculate network requirements. The network requirements may comprise capacity requirements.
The first station may be a mobile station and the second station may be a base transceiver station. The wireless communication network may use code division multiple access. Embodiments of the present invention are particularly advantageous when used in conjunction with a CDMA network. Unnecessary attempts to use service may be avoided thus improving capacity. Embodiments of the present invention may be advantageous when used in conjunction with a TDMA network.
According to a second aspect of the present invention, there is provided a method of determining the availability of at least one of a plurality of different services having different requirements in a wireless communication network comprising at least a first station and a second station which are in communication, said method comprising the step of estimating the pathloss between said first station and said second station, and based on said pathloss and the maximum power with which the first station is capable of transmitting, determining the greatest service requirements which can be provided.
According to a third aspect of the present invention, there is provided a method of determining the availability of at least one of a plurality of different services in a wireless communication network comprising at least a first station and a second station which are in communication, said method comprising the step of estimating the interference in the signals transmitted between said first station and said second station, and based on the interference and the requirements of at least one of said services determining the power with which said first station is required to transmit to said second station; and comparing said required power with the maximum power with which the first station is capable of transmitting.